This is from the 2008 NEC
690.13 All Conductors.
Means shall be provided to disconnect all current-carrying conductors
of a photovoltaic power source from all other conductors in a
building or other structure. A switch, circuit breaker, or other
device, either ac or dc, shall not be installed in a grounded
conductor if operation of that switch, circuit breaker, or other
device leaves the marked, grounded conductor in an ungrounded and
energized state.
Exception: A switch or circuit breaker that is part of a
ground-fault detection system required by 690.5 shall be permitted to
open the grounded conductor when that switch or circuit breaker is
automatically opened as a normal function of the device in responding
to ground faults. The switch or circuit breaker shall indicate the
presence of a ground fault.
FPN: The grounded conductor may have a bolted or terminal
disconnecting means to allow maintenance or troubleshooting by
qualified personnel.
At 04:51 AM 9/15/2012, you wrote:
Bob,
The problem with switching both conductors (in a normally grounded
array) is that opening the disconnect removes the bond to ground.
This takes the ground fault protection and detection system out of
the scheme (which would at least have operated with the disconnect
open on the normally ungrounded conductor).
An inspector should appreciate the value of maintaining the
functionality of the ground fault protection system. 690.13 makes
this clear, by allowing the grounded conductor to be disconnected by
service personnel.
Isaac Opalinsky
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